Organometallic tin compounds as EUV photoresist

ABSTRACT

The present disclosure is related to organometallic sandwich and half-sandwich tin (bearing η5-C5—Sn π bond) compounds as extreme ultraviolet (EUV) photoresist. Organometallic sandwich di(cyclopentadienyl)tin dialkoxide represented by the chemical formula (η5-C5R5)2Sn(OR1)(OR2), or half-sandwich (cyclopentadienyl)tin triamide represented by the chemical formula (η5-C5R5)Sn(NR12)(NR22)(NR32) are described including the methods for preparation and purification, wherein R1, R2, R3 are independently H, linear or branched alkyl, alkenyl, alkynyl, or cycloalkyl group with 1 to 20 carbon atoms, or aryl group with 6-20 carbon atoms. Sandwich and half-sandwich groups comprise cyclopentadienyl (C5H5), or substituted cyclopentadienyl (η5-C5H4R, η5-C5H3R2, η5-C5H2R3, η5-C5HR4, or η5-C5R5). The solution compositions of organometallic sandwich and half-sandwich tin (bearing η5-C5—Sn π bond) compounds are suitable for EUV photoresists, and/or the precursors of EUV photoresists for radiation sensitive coating and forming nanoscale patterns through photolithography.

FIELD OF THE INVENTION

The present invention relates to organometallic sandwich and half-sandwich tin (bearing η⁵-C₅—Sn π bond) compounds as EUV photoresists, and/or the precursor for EUV photolithography.

BACKGROUND OF THE INVENTION

With the development of the semiconductor industry, nanoscale patterns have been in pursuit of higher devices density, higher performance, and lower costs. Reducing semiconductor feature size has become a grand challenge. Photolithography has been applied for creating microelectronic patterns over decades. Extreme ultraviolet (EUV) lithography is under development for mass production of smaller semiconductor devices feature size and increasement of devise density on a semiconductor wafer. EUV lithography is a pattern-forming technology using wavelength of 13.5 nm as an exposure light source to manufacture high-performance integrated circuits containing high-density structures patterned with nanometer scale. The application of EUV lithography can make extremely fine pattern with smaller width as equal to or less than 7 nm. Therefore, EUV lithography becomes one significant tool and technology for manufacturing next generation semiconductor devices.

In order to improve EUV lithography for smaller level, wafer exposure throughput can be improved through increased exposure power or increased photoresist sensitivity. Photoresists are radiation sensitive materials upon irradiation with relevant chemical transformation occurs in the exposed region, which would result in different solubility in developer solution between the exposed and non-exposed regions. The properties of EUV photoresist such as resolution, sensitivity, line edge roughness (LER), line width roughness (LWR), etch resistance and ability to form thinner layer are important in photolithography.

Organometallic compounds have high EUV light adsorption because metals have high adsorption capacity of EUV radiation, and then can be used as photoresists and/or the precursors of metal oxides for photolithography at smaller level (e.g. <7 nm), which is of great interests for EUV radiation lithography. As promising advanced materials, organometallic tin compounds can provide photoresist patterning with significant advantages such as improved resolution, sensitivity, etch resistance, and lower line width/edge roughness without pattern collapse because of strong EUV radiation adsorption of tin, which have been demonstrated.

SUMMARY OF THE INVENTION

In a first aspect, the present invention pertains to organometallic sandwich and half-sandwich tin (bearing η⁵-C₅—Sn π bond) compounds as EUV photoresists, and/or as the precursors for EUV lithography. The present invention is to provide preparation and purification methodology of organometallic sandwich and half-sandwich tin (bearing η⁵-C₅—Sn π bond) compounds with high purity suitable for EUV lithography (e.g. <7 nm). The present invention is further to provide an alternative EUV photoresist with higher resolution, sensitivity, and lower line width roughness without pattern collapse during microelectronic patterning. The sensitivity and stability of organometallic sandwich and half-sandwich tin (bearing η⁵-C₅—Sn π bond) compounds are important for high resolution and efficiency of photoresist for EUV lithography.

In another aspect, the described organometallic sandwich and half-sandwich tin (bearing η⁵-C₅—Sn π bond) compounds comprise cyclopentadienyl (η⁵-C₅H₅, or Cp), or substituted cyclopentadienyl (η⁵-C₅H₄R, η⁵-C₅H₃R₂, η⁵-C₅H₂R₃, η⁵-C₅HR₄, or η⁵-C₅R₅), wherein R is H, an alkyl, alkenyl, alkynyl, or cycloalkyl group with 1 to 20 carbon atoms, or an aryl group with 6-20 carbon atoms, including but not limited to, methyl, ethyl, isopropyl, tert-butyl, tert-amyl, sec-butyl, pentyl, hexyl, neopentyl, cyclohexyl, cyclopentyl, cyclobutyl, cyclopropyl, phenyl group. For example, methylcyclopentadienyl (η⁵-C₅H₄Me or η⁵-MeCp), dimethylcyclopentadienyl (η⁵-C₅H₃Me₂ or η⁵-Me₂Cp), trimethylcyclopentaidenyl (η⁵-C₅H₂Me₃ or η⁵-Me₃Cp), tetramethylcyclopentadienyl (η⁵-C₅HMe₄ or η⁵-Me₄Cp), or pentamethylcyclopentadienyl (η⁵-C₅Me₅ or η⁵-Cp*).

In a further aspect, the present disclosure pertains to organometallic sandwich bis(cyclopentadienyl)tin oxide represented by the chemical formula (η⁵-C₅R₅)₂SnO, di(cyclopentadienyl)tin dialkoxide represented by the chemical formula (η⁵-C₅R₅)₂Sn(OR¹)(OR²), and half-sandwich (cyclopentadienyl)tin triamide represented by the chemical formula (η⁵-C₅R₅)Sn(NR¹ ₂)(NR² ₂)(NR³ ₂), wherein R¹, R², R³ are independently H, alkyl (linear or branched), alkenyl, alkynyl, or cycloalkyl group with 1 to 20 carbon atoms, r aryl group with 6-20 carbon atoms, including but not limited to, methyl, ethyl, isopropyl, tert-butyl, tert-amyl, sec-butyl, pentyl, hexyl, neopentyl, cyclohexyl, cyclopentyl, cyclobutyl, cyclopropyl group.

In other aspects, the invention pertains to a method to prepare sandwich bis(cyclopentadienyl)tin oxide represented by the chemical formula (η⁵-C₅R₅)₂SnO, the method comprising the oxidation of bis(cyclopentadienyl)tin (η⁵-C₅H₅)₂Sn with equivalent dried molecular oxygen under ambient conditions like in organic solvents with standard Schlenk techniques.

In another aspect, the invention pertains to a method to prepare sandwich di(cyclopentadienyl)tin dialkoxides represented by the chemical formula (η⁵-C₅R₅)₂Sn(OR¹)(OR²), the method comprising the reactions of (η⁵-C₅H₅)₂SnCl₂ with alcohol in the presence of base like amine in organic solvent under ambient conditions like under inert atmosphere (N₂, Ar) with standard Schlenk techniques, or with alkali alkoxide represented by MOR (M=alkali metal) in organic solvent under ambient conditions.

In an additional aspect, the invention pertains to a method to prepare half-sandwich (cyclopentadienyl)tin triamide represented by the chemical formula (η⁵-C₅R₅)Sn(NR¹ ₂)(NR² ₂)(NR³ ₂), the method comprising the reactions of (η⁵-C₅H₅)SnCl₃ with lithium amides (LiNR¹ ₂) or the like in organic solvents under ambient conditions, such as under inert atmosphere (N₂, Ar) with standard Schlenk techniques.

Furthermore, the present invention pertains to the methods for purification of organometallic sandwich and half-sandwich tin (bearing η⁵-C₅—Sn π bond) compounds. The purification methods include distillation, extraction, filtration, recrystallization, column chromatography, coordination and sublimation, and/or combination thereof.

In a further aspect, a solution composition of organometallic tin compounds EUV photoresist comprises one or more organometallic sandwich and half-sandwich tin (bearing η⁵-C₅—Sn π bond) compounds, solvents, and/or additives.

The organic solvent comprises, including but not limited to, chloroform, dichloromethane, hexane, cyclohexane, tetrahydrofuran, dimethoxyethane, dimethylformamide, dimethyl sulfoxide, alcohols (e.g., methanol, ethanol, propanol, isopropanol, 1-butanol, 4-methyl-2-propanol, 4-methyl-2-pentenol), aromatic solvents (e.g., benzene, toluene, xylene), carboxylic acid, ethers (e.g., anisole, diethyl ether), esters (e.g., ethyl acetate, ethyl lactate, butyl acetate, propylene glycol monomethyl ether acetate), ketone (e.g., acetone, 2-heptanone, methyl ethyl ketone, acetone), or two or more mixtures thereof, and/or the like, but is not limited thereto.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1-27 are chemical formulas of organometallic sandwich and half-sandwich tin (bearing η⁵-C₅—Sn π bond) compounds, wherein sandwich and half-sandwich comprise cyclopentadienyl, or substituted cyclopentadienyl (η⁵-C₅H₄R, η⁵-C₅H₃R₂, η⁵-C₅H₂R₃, η⁵-C₅HR₄, and η⁵-C₅R₅), R can be H, an alkyl, alkenyl, alkynyl, or cycloalkyl group with 1 to 20 carbon atoms, or an aryl group with 6-20 carbon atoms, for example, methylcyclopentadienyl (η⁵-C₅H₄Me or η⁵-MeCp), dimethylcyclopentadienyl (η⁵-C₅H₃Me₂ or η⁵-Me₂Cp), trimethylcyclopentaidenyl (η⁵-C₅H₂Me₃ or η⁵-Me₃Cp), tetramethylcyclopentadienyl (η⁵-C₅HMe₄ or if-Me₄Cp), pentamethylcyclopentadienyl (η⁵-C₅Me₅ or η⁵-Cp*), or other substituted cyclopentadienyl groups, including but not limited to, ethyl, propyl, butyl, pentyl, hexyl, phenyl group. The organometallic sandwich and half-sandwich tin (bearing η⁵-C₅—Sn π bond) compounds are suitable for EUV photoresists, and/or the precursors for EUV lithography.

DETAILED DESCRIPTION OF THE INVENTION

The present disclosure relates to organometallic sandwich and half-sandwich tin (bearing η⁵-C₅—Sn π bond) compounds, which are suitable for EUV photoresists, and/or as the precursors for EUV lithography. The present invention disclosures organometallic sandwich bis(cyclopentadienyl)tin oxide represented by the chemical formula (η⁵-C₅R₅)₂SnO, di(cyclopentadienyl)tin dialkoxide represented by the chemical formula (η⁵-C₅R₅)₂Sn(OR¹)(OR²), and half-sandwich (cyclopentadienyl)tin triamide represented by the chemical formula (η⁵-C₅R₅)Sn(NR¹ ₂)(NR² ₂)(NR³ ₂), including the methods for preparation and purification.

As described herein, the singular forms “a”, “an”, “one”, and “the” are intended to include the plural forms as well, unless clearly indicated otherwise. Further, the expression “one of,” “at least one of,” “any”, and “selected from,” when preceding a list of elements, modify the entire list of elements and do not modify the individual elements of the list.

As described herein, the terms “includes”, “including”, “comprise”, “comprising”, when used in this specification, specify the presence of the stated features, steps, operations, elements, components, but do not preclude the presence or addition of one or more other features, steps, operations, elements, components, and/or group thereof.

As described herein, the term “and/or” includes any and all combinations of one or more of the associated listed items. Further, the use of “may” when describing embodiments of the present disclosure refers to “one or more embodiments of the present disclosure”.

As described herein, the terms “use,” “using,” and “used” may be considered synonymous with the terms “utilize,” “utilized”, “applied”, respectively. In addition, the terms “about,” “only,” and similar terms are used as terms of approximation and not as terms of degree, and are intended to account for the inherent deviation in measured or calculated values that would be recognized by those of ordinary skill in the art.

The term “alkyl” or “alkyl group” refers to a saturated linear or branched-chain hydrocarbon of 1 to 20 carbon atoms. The term “alkenyl, alkynyl, cycloalkyl” refers to hydrocarbon of 1 to 20 carbon atoms. The term ‘aryl” refers to aromatic group with 6-20 carbon atoms.

EUV lithography is under the development for the mass production of next generation <7 nm node. EUV photoresists are required to achieve higher performance, higher sensitivity and resolution, and cost reduction.

EUV light has been applied for photolithography at about 13.5 nm. The EUV light can be generated from Sn plasma or Xe plasma source excited using high energy lasers or discharge pulses.

Organometallic photoresists are used in EUV lithography because metals have high adsorption capacity of EUV radiation. Radiation sensitivity and thermal-, oxygen- and moisture-stability are important for organometallic photoresists. In some embodiments, organometallic photoresists may adsorb moisture and oxygen, which may result in decreasing stability, as well decreasing solubility in developer solutions. In addition, in some embodiments, photoresist layer may outgas volatile components prior to the radiation exposure and development operations, which may negatively affect the lithography performance, pattern collapse and increase defects.

In general, metal central of organometallic EUV photoresist plays the key role in determining the absorption of radiation. Tin has strong absorption of EUV light at 13.5 nm. The organic ligands bonded to tin atom may also has absorption of EUV light. The tuning and modification of organic ligands can change the sensitivity, resolution and radiation absorption, and the desired control of the material properties.

Organometallic tin photoresist layer is patterned by exposure to actinic radiation. Typically, the chemical properties of the photoresist regions struck by incident radiation change in a manner that depends on the type of photoresist used. Photoresist can be positive resist or negative resist. In some embodiments, positive resist refer to a photoresist material that when exposed to radiation (e.g., EUV) becomes soluble in a developer, while the region of the photoresist that is non-exposed (or exposed less) is insoluble in the developer. In some embodiments, on the contrary, negative resist refers to a photoresist material that when exposed to radiation becomes insoluble in the developer, while the region of the photoresist that is non-exposed (or exposed less) is soluble in the developer.

The organometallic tin compounds possess excellent properties as photoresists for the application in EUV lithographic patterning. Suitable organometallic tin photoresists are described in U.S. Patents and Patent Applications, for example, U.S. Pat. No. 10,732,505 B1; 2019/0315781 A1; 2019/0315782 A1; 2021/0024552 A1; 2021/0198293 A1; U.S. Pat. Nos. 10,642,153 B2; 10,228,618 B2; 10,775,696 B2; 2020/0257196 A1; filed by Inpria Corporation; U.S. Pat. No. 11,092,890 B2; 2021/0356861 A1; 2021/0311387 A1; and 2021/0333708 A1 filed by Samsung SDI Co., Ltd.; all of which are incorporated herein by references. These US. Patents and Patent Applications described carbon atom of aliphatic and aromatic groups bonded to tin atom as single bond η¹-C—Sn (one carbon atom of a ligand bonded to one tin atom), for example, t-BuSn(NMe₂)₃ and t-BuSn(O-t-Bu)₃.

The organometallic sandwich and half-sandwich tin (bearing η⁵-C₅—Sn π bond, five carbon atoms of cyclopentadienyl group simultaneously bonded to one tin atom) compounds represented by Chemical Formulas FIG. 1-27 contain tin atom, which may have strong adsorption of EUV light at about 13.5 nm and thus may have excellent (or suitable) sensitivity to EUV light, and can be used as radiation sensitive organotin EUV photoresists, and/or as the precursors for the preparation of organotin EUV photoresists and photolithography patterning.

In the Chemical Formulas FIG. 1-27 , R is H, an alkyl, alkenyl, alkynyl, or cycloalkyl group with 1 to 20 carbon atoms r aryl group with 6-20 carbon atoms, and R¹, R², R³ are independently H, alkyl (linear or branched), alkenyl, alkynyl, or cycloalkyl group with 1 to 20 carbon atoms, or aryl group with 6-20 carbon atoms. Sandwich and half-sandwich comprise cyclopentadienyl (η⁵-C₅H₅, or Cp), substituted cyclopentadienyl (η⁵-C₅H₄R, η⁵-C₅H₃R₂, η⁵-C₅H₂R₃, η⁵-C₅HR₄, or η⁵-C₅R₅), for example, methylcyclopentadienyl (η⁵-C₅H₄Me or η⁵-MeCp), dimethylcyclopentadienyl (η⁵-C₅H₃Me₂ or η⁵-Me₂Cp), trimethylcyclopentaidenyl (η⁵-C₅H₂Me₃ or η⁵-Me₃Cp), tetramethylcyclopentadienyl (η⁵-C₅HMe₄ or η⁵-Me₄Cp), pentamethylcyclopentadienyl (η⁵-C₅Me₅ or η⁵-Cp*), or other alkyl/aryl substituted cyclopentadienyl groups, including, but not limited to, methyl, ethyl, propyl, butyl, pentyl, hexyl, phenyl group.

The organometallic sandwich and half-sandwich tin (bearing η⁵-C₅—Sn π bond) compounds contain η⁵-cyclopentadiene-Sn bond (η⁵-C₅—Sn bond, five carbon atoms of cyclopentadienyl ligand simultaneously bonded to one tin atom), such as (η⁵-C₅H₅)₂Sn(O^(t)Bu)₂. π bonded η⁵-C₅—Sn is sensitive to UV light, which has been demonstrated, for example, P. J. Baker, A. G. Davies, M.-W. Tse, “The Photolysis of Cyclopentadienyl Compounds of Tin and Mercury. Electron Spin Resonance Spectra and Electronic Configuration of the Cyclopentadienyl, Deuteriocyclopentadienyl, and Alkylcyclopentadienyl Radicals”, Journal of Chemical Society, Perkin II, 1980, 941-948; S. G. Baxter, A. H. Cowley, J. G. Lasch, M. Lattman, W. P. Sharum, C. A. Stewart, “Electronic Structures of Bent-Sandwich Compounds of the Main-Group Elements: A Molecular Orbital and UV Photoelectron Spectroscopic Study of Bis(cyclopentadienyl)tin and Related Compounds”, Journal of the American Chemical Society, 1982, 104, 4064-4069, all of which are incorporated herein by references.

(η⁵-C₅R₅) of the Chemical Formulas FIG. 1-27 may impart photosensitivity to the compounds, and the η⁵-C₅—Sn π bond formed may promote suitable solubility in an organic solvent to the organometallic sandwich and half-sandwich tin compounds. Accordingly, these η⁵-C₅—Sn π bond containing organometallic sandwich and half-sandwich tin compounds according to an embodiment may have improved sensitivity, resolution and stability, and may suitable for EUV photoresists, and/or the precursors for EUV lithography to form tin oxide or tin oxide hydroxide film.

The organometallic sandwich and half-sandwich tin (bearing η⁵-C₅—Sn π bond) compounds as EUV photoresists may have excellent sensitivity and resolution, lower line edge and width roughness.

As one of ordinary skill in the art will recognize, the chemical compounds listed here are merely intended as illustrated examples of the organometallic sandwich and half-sandwich tin (bearing η⁵-C₅—Sn π bond) compounds, and are not intended to limit the embodiments to only those organometallic sandwich and half-sandwich tin (bearing η⁵-C₅—Sn π bond) compounds specifically described. Rather, any suitable organometallic sandwich and half-sandwich tin (bearing η⁵-C₅—Sn π bond) compounds may be used, and all such organometallic sandwich and half-sandwich tin (bearing η⁵-C₅—Sn π bond) compounds are fully intended to be included within the scope of the present embodiments.

The organometallic sandwich and half-sandwich tin (bearing η⁵-C₅—Sn π bond) compounds comprise di(cyclopentadienyl)tin (η⁵-C₅R₅)Sn based represented by chemical formulas FIGS. 1-10 , and (cyclopentadienyl)tin (η⁵-C₅R₅)Sn based represented by the Chemical Formulas FIGS. 11-27 . Cyclopentadienyl group represents cyclopentadienyl, and substituted cyclopentadienyl (η⁵-C₅H₄R, η⁵-C₅H₃R₂, η⁵-C₅H₂R₃, η⁵-C₅HR₄, or η⁵-C₅R₅ group), R can be H, an alkyl, alkenyl, alkynyl, or cycloalkyl group with 1 to 20 carbon atoms or an aryl group with 6-20 carbon atoms, including but not limited to, methyl, ethyl, propyl, butyl, hexyl, phenyl group.

In the present disclosure, the term “substituted” refers to replacement of a hydrogen atom with a C1 to C20 alkyl group, a C1 to C20 alkene group, a C1 to C20 alkyne group, a C1 to C20 cycloalkyl group, a C6 to C20 aryl group, or other relevant groups.

In the present disclosure, the organometallic sandwich and half-sandwich tin (bearing η⁵-C₅—Sn π bond) compounds include, but not limited to, bis(cyclopentadienyl)tin oxide, di(cyclopentadienyl)tin dialkoxide and (cyclopentadienyl)tin triamide, and the preparation and purification methods with high purity for microelectronic EUV lithography patterning.

One or more examples embodiments of the present disclosure provide a semiconductor EUV photoresist composition according to an embodiment as hereinafter described.

A semiconductor EUV photoresist composition according to an embodiment of the present disclosure includes (e.g., consist of) organometallic sandwich and half-sandwich tin (bearing η⁵-C₅—Sn π bond) compounds represented by Chemical Formulas FIG. 1-27 .

In an embodiment, the organometallic sandwich and half-sandwich tin (bearing η⁵-C₅—Sn π bond) compounds according to the embodiments of the present disclosure may be represented by at least one of Chemical Formulas FIG. 1 to 27 .

The organometallic sandwich and half-sandwich tin (bearing η⁵-C₅—Sn π bond) compound photoresist composition according to embodiments of the present disclosure may have relatively improved photosensitivity, resolution, and etch resistance, wherein cyclopentadienyl (η⁵-C₅, or η⁵-Cp) or substituted cyclopentadienyl, oxygen or various other groups are bonded to tin atom.

The organometallic sandwich and half-sandwich tin (bearing η⁵-C₅—Sn π bond) compounds, represented by the Chemical Formulas FIG. 1-27 , are soluble in appropriate organic solvents for further pattern processing. The solution composition of organometallic sandwich and half-sandwich tin (bearing η⁵-C₅—Sn π bond) compound photoresist can be formed by dissolving the relevant compound in organic solvents, include, but not limit to, chloroform, dichloromethane, hexane, cyclohexane, tetrahydrofuran (THF), dimethoxyethane (DME), dimethylformamide (DMF), dimethyl sulfoxide (DMSO), alcohols (e.g., methanol, ethanol, propanol, butanol, 4-methyl-2-propanol, 4-methyl-2-pentenol), aromatic solvents (e.g., benzene, toluene, xylene), carboxylic acid, ethers (e.g. diethyl ether, anisole), esters (e.g. ethyl acetate, ethyl lactate, butyl acetate, propylene glycol monomethyl ether acetate), ketone (e.g., acetone, 2-heptanone, 4-methyl-2-pentanone, methyl ethyl ketone), or two or more mixtures thereof, and/or the like, but is not limited thereto. The solution compositions of organometallic sandwich and half-sandwich tin (bearing η⁵-C₅—Sn π bond) compounds can be utilized as photoresists for further processing and lithography patterning. A person of ordinary skills in the art will recognize that the choice of solvents and solution composition components within the explicit ranges of above are contemplated and are within the present disclosure.

The solubility of organometallic sandwich and half-sandwich tin (bearing η⁵-C₅—Sn π bond) compounds in organic solvents may be improved during an EUV exposure. Accordingly, a nanoscale pattern having improved sensitivity and resolution may be afforded by using organometallic sandwich and half-sandwich tin (bearing η⁵-C₅—Sn π bond) compounds. Additionally, the as-formed pattern by using of organometallic sandwich and half-sandwich tin (bearing η⁵-C₅—Sn π bond) compounds may not collapse while having a high aspect ratio.

In some embodiments, the organometallic sandwich and half-sandwich tin (bearing η⁵-C₅—Sn π bond) compounds comprising a hydrolyzed group can be used as precursor compositions to form organotin oxo-hydroxo patterning composition by water or other suitable reagents under appropriate conditions. For example, the half-sandwich organotin oxo-hydroxo can be represented by the chemical formula (η⁵-C₅R₅)SnO(OH) (η⁵-C₅R₅═C₅H₅, or other substituted cyclopentadienyls). The hydrolyzed groups can be alkoxide, ester, amide, halogen, but not limited to.

The organometallic sandwich and half-sandwich tin (bearing η⁵-C₅—Sn π bond) compounds photoresist may have high sensitivity (low expose dose, e.g. <20 mJ/cm²) and excellent performance; low or free pattern defectivity at nanoscale. The organometallic sandwich and half-sandwich tin (bearing η⁵-C₅—Sn π bond) compounds photoresist may have tight pitch (e.g. <10 nm), and may sustain the yield and deliver high resolution.

In an embodiment, organometallic sandwich bis(cyclopentadienyl)tin oxide, is represented by the chemical formula (η⁵-C₅R₅)₂SnO, di(cyclopentadienyl)tin dialkoxide is represented by the chemical formula (η⁵-C₅R₅)₂Sn(OR¹)(OR²), and half-sandwich (cyclopentadienyl)tin triamide is represented by the chemical formula (η⁵-C₅R₅)Sn(NR¹ ₂)(NR² ₂) (NR³ ₂), wherein R is H, an alkyl, alkenyl, alkynyl, or a cycloalkyl group with 1 to 20 carbon atoms, or an aryl group with 6-20 carbon atoms, and R_(, R) ², R³ are independently H, alkyl (linear or branched), alkenyl, alkynyl, or cycloalkyl group with 1 to 20 carbon atoms, or aryl group with 6-20 carbon atoms.

Examples of specific organometallic sandwich and half-sandwich tin (bearing η⁵-C₅—Sn n bond) compounds that may be used in implementations of the invention including (η⁵-C₅R₅)₂SnO, (η⁵-C₅R₅)₂Sn(OR¹)(OR²), (η⁵-C₅R₅)Sn(NR¹ ₂)(NR² ₂)(NR³ ₂), wherein R is H, an alkyl, alkenyl, alkynyl, or a cycloalkyl group with 1 to 20 carbon atoms, or an aryl group with 6-20 carbon atoms, and R¹, R², R³ are independently H, alkyl (linear or branched), alkenyl, alkynyl, or cycloalkyl group with 1 to 20 carbon atoms, r aryl group with 6-20 carbon atoms.

All chemical manipulations, including preparation and purification, are performed under an inert atmosphere of purified nitrogen or argon in dry and degassed solvents by employing standard Schlenk techniques. The methods for purification of organometallic sandwich and half-sandwich tin (bearing η⁵-C₅—Sn π bond) compounds comprise distillation, extraction, filtration, recrystallization, column chromatography, coordination and sublimation, and combinations thereof.

In some embodiments, organometallic sandwich bis(cyclopentadienyl)tin oxide, represented by the chemical formula (η⁵-C₅R₅)₂SnO, are prepared from the reactions of bis(cyclopentadienyl)tin with equivalent dried molecular oxygen under ambient conditions like in organic solvents with standard Schlenk techniques, wherein R is H, an alkyl, alkenyl, alkynyl, or a cycloalkyl group with 1 to 20 carbon atoms, or an aryl group with 6-20 carbon atoms.

In some embodiments, organometallic sandwich di(cyclopentadienyl)tin dialkoxide represented by the chemical formula (η⁵-C₅R₅)₂Sn(OR¹)(OR²), are prepared from the reactions of (η⁵-C₅R₅)₂SnX₂ (X═F, Cl, Br, I) with related organic alcohols in the presence of bases like trimethylamine under ambient conditions like in organic solvents with standard Schlenk techniques, wherein R is H, an alkyl, alkenyl, alkynyl, or a cycloalkyl group with 1 to 20 carbon atoms, or an aryl group with 6-20 carbon atoms, and R¹, R², are independently H, alkyl (linear or branched), alkenyl, alkynyl, or cycloalkyl group with 1 to 20 carbon atoms, or aryl group with 6-20 carbon atoms. Additionally, in some embodiments, organometallic sandwich di(cyclopentadienyl)tin dialkoxide can be prepared from the reactions of (η⁵-C₅R₅)₂SnX₂ (X═F, Cl, Br, I) with alkali alkoxide bases (ROM, M=alkali metal), for example, ^(r)BuOK, ^(i)PrONa, EtONa, MeONa or the like under ambient conditions like in organic solvents with standard Schlenk techniques. A person of ordinary skills in the art will recognize that additional bases and reaction conditions within the explicit ranges of above are contemplated and are within the present disclosure.

In some embodiments, organometallic half-sandwich (cyclopentadienyl)tin triamides represented by the chemical formula (η⁵-C₅R₅)Sn(NR¹ ₂)(NR² ₂)(NR³ ₂), are prepared from the reactions of (η⁵-C₅R₅)SnX₃ (X═F, Cl, Br, I) with lithium amides (LiNR¹ ₂) or the like under ambient conditions like in organic solvents with standard Schlenk techniques, wherein R is H, an alkyl, alkenyl, alkynyl, or a cycloalkyl group with 1 to 20 carbon atoms, or an aryl group with 6-20 carbon atoms, and R_(, R) ², R³ are independently H, alkyl (linear or branched), alkenyl, alkynyl, or cycloalkyl group with 1 to 20 carbon atoms, r aryl group with 6-20 carbon atoms. A person of ordinary skills in the art will recognize that additional bases and reaction conditions within the explicit ranges of above are contemplated and are within the present disclosure.

Organometallic tin EUV photoresists comprising monoalkyl tin triamide compounds represented by the chemical formula RSn(NR¹ ₂)₃ are described, for example, in U.S. Pat. No. 10,975,109 B2 to Edson et al., entitled “Monoalkyl Tin Compounds with Low Polyalkyl Contamination, Their Compositions and Methods;” U.S. Pat. No. 10,787,466 B2 to Edson et al., entitled “Monoalyl Tin Compounds with Low Polyalkyl Contamination, Their Compositions and Methods”, which are incorporated herein by references.

Organometallic sandwich and half-sandwich tin (bearing η⁵-C₅—Sn π bond) compound impurities may result in contamination and defect for photolithography. In some embodiments, the impurities can be the mixtures of mono, bi, or tri-substituted tin compounds, for example, but not limited to, (η⁵-C₅R₅)₂Sn(OR¹)X, (η⁵-C₅R₅)Sn(NR¹ ₂)X₂, or (η⁵-C₅R₅)Sn(NR¹ ₂)(NR² ₂)X, X═F, Cl, Br, I, or from other unseparated reactants and side-products.

In one or more embodiments, the semiconductor EUV photoresists composition according to an embodiment may include one or more organometallic sandwich and half-sandwich tin (bearing η⁵-C₅—Sn π bond) compounds, a solvent, and/or an additive.

In general, the organic solvents selection can be determined by solubility, boiling point, reactivity, volatility, viscosity, flammability, and toxicity. The potential hydration and/or condensation may occur after organometallic tin compounds photoresists dissolve in organic solvent, and the characters of the species may change as a result of partial hydration and condensation, especially during the coating process. When the composition of the solution is references herein, the reference is to the component as added to the solution, since complex formulation may produce metal polynuclear species, and/or metal-containing nanoclusters in solution that may not be well characterized.

In some embodiments, the organometallic sandwich and half-sandwich tin (bearing η⁵-C₅—Sn π bond) compounds, represented by the Chemical Formulas FIG. 1-27 , may be used as precursors to form tin-containing nanoclusters for EUV photolithography. In some embodiments, two or more organometallic tin compounds are used thereof.

The solvent of the organometallic tin photoresists composition according to the embodiment may be an organic solvent, and in some embodiments, may include, chloroform, dichloromethane, hexane, cyclohexane, tetrahydrofuran, dimethoxyethane, dimethylformamide, dimethyl sulfoxide, alcohols (e.g., methanol, ethanol, propanol, butanol, 4-methyl-2-propanol, 4-methyl-2-pentenol), aromatic solvents (e.g., benzene, toluene, xylene), carboxylic acid, ethers (e.g. diethyl ether, anisole), esters (e.g. ethyl acetate, ethyl lactate, butyl acetate, propylene glycol monomethyl ether acetate), ketone (e.g., acetone, 2-heptanone, 4-methyl-2-pentanone, methyl ethyl ketone), or two or more mixtures thereof, and/or the like, but is not limited thereto.

In some embodiments, the organometallic sandwich and half-sandwich tin (bearing η⁵-C₅—Sn π bond) compounds photoresist composition may also contain an additive, besides organometallic tin compound and solvent.

In some embodiments, the additive can be used to purify the impurities of trace metals or metallic complexes by-products. In some embodiments, the additives consist of molecular chelating agents, including but not limited to phosphine ligand, amines, polyamines, alcohol amines, amino acids, biomolecules, e.g. ethylenediamine-tetra acetic acid (EDTA), chitosan, cellulose, glycol, but not limited to.

In some embodiments, the additive can be a resin. The resin may be organic polymer, or small organic aromatic molecules. In some embodiments, the additive can be a surfactant. In some embodiments, the additive can be a water adsorbent, such as glycol, but not limited to. In some embodiments, the additive can be an adhesion additive, such as a silane. In some embodiments, the additive can be a protective polymer, such as a fluorinated polymer.

The organometallic sandwich and half-sandwich tin (bearing η⁵-C₅—Sn π bond) compounds absorb EUV radiation after exposed to EUV, sandwich ligand and one or more R¹, R², R³ group are cleaved from the organometallic sandwich and half-sandwich tin (bearing η⁵-C₅—Sn π bond) compounds to form tin oxide or tin oxide hydroxide pattern. In some embodiments, the unexposed area of the substrate surface may be removed by the developer.

Additionally, the organometallic sandwich and half-sandwich tin (bearing η⁵-C₅—Sn π bond) compounds photoresist pattern according to an embodiment is not necessarily limited to the negative tone image but may be formed to have a positive tone image.

In some embodiments, the developer compositions for as-formed patters can be any suitable organic solvent, or aqueous solution, at low to high concentrations. In some embodiments, non-limiting examples of the organic solvent used in the method of forming patterns, the organic solvent can be one or more selected from, but not limited to, for example, chloroform, dichloromethane, hexane, cyclohexane, tetrahydrofuran, dimethoxyethane, dimethylformamide, dimethyl sulfoxide, ethyl lactate, n-butyl acetate, dioxane, ketones (e.g., acetone, 2-heptanone, methylethylketone, cyclohexanone, γ-butyrolactone, and/or the like), alcohols (e.g., methanol, ethanol, 1-propanol, isopropanol, 1-butanol, 4-methyl-2-propanol, 1-ethoxy-2-propanol, methyl isobutyl carbinol, and/or the like), carboxylic acid, ethers (e.g., anisole, diethyl ether, propylene glycol monomethyl ether, and/or the like), esters (e.g., ethyl acetate, n-butyl acetate, butyrolactone, propylene glycol monomethyl ester acetate, and/or the like), aromatic solvents (e.g. benzene, toluene, xylene, and/or the like), and combinations thereof.

Hereinafter, the present invention is described in more details through Examples regarding to the preparation of the organometallic sandwich and half-sandwich tin (bearing η⁵-C₅—Sn π bond) compounds photoresist of the present embodiments. However, the present invention is not limited by the Examples. The following examples are provided for further illustration of certain embodiments of the disclosure, which is not necessarily limited to these embodiments.

EXAMPLES Example 1 Synthesis of (η⁵-C₅H₅)₂Sn

This example and the followings provide the solid evidences for the synthesis of organometallic tin complexes. The Schlenk lines with stand techniques like dried organic solvents under dried inert dinitrogen or argon atmosphere are utilized for the synthesis of organometallic tin compounds.

Bis(cyclopentadienyl)tin(II) or (stannocene) was synthesized according to the reference: C. Janiak, Zeitschrift für Anorganische und Allgemeine Chemie, 2010, 636 (13-14), 2387-2391. C₅H₅Na was prepared from freshly distilled C₅H₆ with sodium sand in tetrahydrofuran (THF) at room temperature until all the solid sodium sand disappeared. After decanted the THF solution, and removal of all the volatiles under vacuum afforded C₅H₅Na as white powder (96% yield). To the solution of C₅H₅Na (1.76 g, 20 mmol) in THF (100 ml) at 0° C., SnCl₂ (1.89 g, 10 mmol) was added with vigorously stirring. After stirred for hours, all the volatiles were removed in vacuum to afford (C₅H₅)₂Sn. The product was obtained by sublimation under vacuum as pale yellow solid (60% yield).

Example 2 Synthesis of (η⁵-C₅H₅)₂SnO

Bis(cyclopentadienyl)tin oxide was synthesized according to the reference: P. G. Harrison and J. J. Zuckerman, Journal of American Chemical Society, 1969, 19, 6885-6886. To the frozen benzene solution of (C₅H₅)₂Sn (2.49 g, 10 mmol), dried equivalent molecular oxygen (0.126 ml, 10 mmol) was introduced. The mixture were slowly warmed to room temperature with vigorously stirring. Then the obtained resultant was evaporated under vacuum to result in (C₅H₅)₂SnO (2.11 g, yield 79.6%). The analytically pure product was recrystallized from benzene and hexane. ¹H NMR (298 K, 400.13 MHz, C₆D₆) δ=5.98. MS (EI): m/z 265 (M⁺ ⁻ ).

Example 3 Synthesis of (η⁵-C₅H₅)₂SnCl₂

Under N₂ atmosphere, (η⁵-C₅H₅)₂SnCl₂ was prepared by the reaction of two equivalent C₅H₅Na or C₅H₅Li with one equivalent SnCl₄ at low temperature, which was according to the reference: P. Jutzi, F. Kohl, Journal of Organometallic Chemistry 164 (1979) 141-152. To the solution of C₅H₅Li (20 mmol) in diethyl ether (100 ml) at −20° C., which was prepared from 1.322 g (20 mmol) of freshly distilled cyclopentadiene (C₅H₆) and 12.5 mL of a 1.6 M solution of n-butyllithium in hexane (20 mmol), SnCl₄ (2.6 g, 1.18 ml, 10 mmol) (Caution: extremely hydrolytic when exposure to air or water and releasing HCl gaseous !!!) in 10 ml diethyl ether was added with vigorously stirring. After stirred for 12 hours, the resultant was filtered through Celite. The filtrate was removed in vacuum to afford (η⁵-C₅H₅)₂SnCl₂ (2.61 g, 81%). The analytically pure product was obtained by sublimation under high vacuum.

Example 4 Synthesis of (η⁵-C₅H₅)₂Sn(O^(t)Bu)₂

This example presents the preparation of (η⁵-C₅H₅)₂Sn(O^(t)Bu)₂ through the alcoholysis reaction of (η⁵-C₅H₅)₂SnCl₂ with t-butanol in the presence of amine under ambient condition. The compound represented by (η⁵-C₅H₅)₂SnCl₂ (1 g, 3.12 mmol) was dissolved in 100 ml of tetrahydrofuran, and then the resulting solution was cooled down to 0° C., followed by the dropwise addition of freshly distilled triethylamine (0.7 ml, 6.8 mmol). Then ^(t)BuOH (5 ml) was added to the mixture with vigorously stirring. After stirred at room temperature for hours, the mixture was filtered, and all the volatiles were removed in vacuum. The residue was extracted by benzene and filter through Celite, then followed by evaporation in vacuum to afford (η⁵-C₅H₅)₂Sn(O^(t)Bu)₂ (1.1 g, yield 89%). ¹H NMR (298 K, 400.13 MHz, C₆D₆) δ=5.88 (s, 10H), 1.37 (s, 18H). MS (EI): m/z (relative intensity) 395 (M⁺). Elemental analysis of C₁₈H₂₈O₂Sn (394.89), anal. calculated C: 54.75%; H: 7.09; and found C: 55.12; H, 7.68.

Example 5 Synthesis of (η⁵-C₅H₅)SnCl₃

(η⁵-C₅H₅)SnCl₃ was prepared by the reaction of equivalent C₅H₅Na or C₅H₅Li with equivalent SnCl₄ in benzene at −78° C., which was according to the reference: U. Schroer, H.-J. Albert, and W. P. Neumann, Journal of Organometallic Chemistry 1975, 102, 291. The solution of C₅H₅Na in THF (in 1:1 molecular ratio) was added dropwise to the solution of SnCl₄ at −78° C. After stirred at r.t. overnight, the mixture were filtered through short pad of Celite. The filtration was evaporated in vacuum to result in (η⁵-C₅H₅)SnCl₃ as yellow oil. The purification was carried out by vacuum fractional distillation.

Example 6 Synthesis of (η⁵-C₅H₅)Sn(NMe₂)₃

This example presents the preparation of (η⁵-C₅H₅)Sn(NMe₂)₃ through the reaction of (η⁵-C₅H₅)SnCl₃ with LiNMe₂.

At −78° C. under N₂ atmosphere, to the solution of LiNMe₂ (1.02 g, 20 mmol) in diethyl ether, the solution of (η⁵-C₅H₅)SnCl₃ (3.56 g, 10 mmol) in tetrahydrofuran (100 ml) was added dropwise with vigorously stirring. After addition, the mixture was stirred at room temperature overnight. Then the mixture was evaporated in vacuum. The residue was extracted by diethyl ether and filtered through Celite. The filtration was evaporated in vacuum to afford (η⁵-C₅H₅)Sn(NMe₂)₃(2.27 g, yield 72%). ¹H NMR (298 K, 400.13 MHz, C₆D₆) δ=5.98 (s, 5H), 2.83 (s, 18H). MS (EI): m/z 316 (M⁺). Elemental analysis of C₁₁H₂₃N₃Sn (315.82), anal. calculated C: 41.83%; H: 7.28, and found C: 42.26; H, 7.88.

It is understood that the above-described examples and embodiments are intend to be illustrative purpose only. It should be apparent that the present invention has described with references to particular embodiments, and is not limited to the example embodiment as described, and may be variously modified and transformed. A person with ordinary skill in the art will recognize that changes can be made in form and detail without departing from the sprit and scope of this invention. Accordingly, the modified or transformed example embodiments as such may be understood from the technical ideas and aspects of the present invention, and the modified example embodiments are thus within the scope of the appended claims of the present invention and equivalents thereof. 

What is claimed is:
 1. Organometallic sandwich di(cyclopentadienyl)tin dialkoxides represented by the chemical formula (η⁵-C₅R₅)₂Sn(OR¹)(OR²), or half-sandwich (cyclopentadienyl)tin triamide represented by the chemical formula (η⁵-C₅R₅)Sn(NR¹ ₂)(NR² ₂)(NR³ ₂), wherein the sandwich and half-sandwich compounds bear a η⁵-C₅—Sn π bond, wherein R is H, alkyl, alkenyl, alkynyl, cycloalkyl group with 1 to 20 carbon atoms, or aryl group with 6-20 carbon atoms, and R¹, R², R³ are independently H, linear or branched alkyl, alkenyl, alkynyl or cycloalkyl group with 1 to 20 carbon atoms, or aryl group with 6-20 carbon atoms.
 2. The organometallic sandwich or half-sandwich tin compounds of claim 1 wherein η⁵-C₅R₅ is η⁵-C₅H₅, η⁵-C₅H₄R, η⁵-C₅H₃R₂, η⁵-C₅H₂R₃, η⁵- C₅HR₄, or η⁵-C₅R₅, and R is an alkyl, alkenyl, alkynyl, cycloalkyl group with 1 to 20 carbon atoms or an aryl group with 6-20 carbon atoms.
 3. A solution comprising the organometallic sandwich represented by the chemical formula (η⁵-C₅R₅)₂Sn(OR¹)(OR²) of claim 1 or the organometallic half-sandwich represented by chemical formula (η⁵-C₅R₅)Sn(NR¹ ₂)(NR² ₂)(NR³ ₂) of claim 1, a solvent, and/or an additive.
 4. A method of forming a pattern, comprising forming an organometallic tin photoresist layer over a substrate, wherein the organometallic tin photoresist comprises the organometallic sandwich represented by the chemical formula (η⁵-C₅R₅)₂Sn(OR¹)(OR²) of claim 1 or the organometallic half-sandwich represented by chemical formula (η⁵-C₅R₅)Sn(NR¹ ₂)(NR² ₂)(NR³ ₂) of claim 1 exposing the photoresist layer to EUV to form a pattern and removing either an unexposed or an exposed area of the exposed photoresist layer through a developer. 